1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Taya2010 [7]
3 years ago
13

Say a hacker has a list of n distinct password candidates, only one of which will successfully log her into a secure system. a.

If she tries passwords from the list at random, deleting those passwords that do not work, what is the probability that her first successful login will be (exactly) on her k-th try?
Mathematics
1 answer:
alexdok [17]3 years ago
7 0

Answer:

The probability is \frac{1}{n}

Step-by-step explanation:

If she has n distinct password candidates and only one of which will successfully log her into a secure system, the probability that her first first successful login will be on her k-th try is:

If k=1

P = \frac{1}{n}

Because, in her first try she has n possibles options and just one give her a successful login.

If k=2

P=\frac{n-1}{n} *\frac{1}{n-1} =\frac{1}{n}

Because, in her first try she has n possibles options and n-1 that are not correct, then, she has n-1 possibles options and 1 of that give her a successful login.

If k=3

P=\frac{n-1}{n} *\frac{n-2}{n-1} *\frac{1}{n-2} = \frac{1}{n}

Because, in her first try she has n possibles options and n-1 that are not correct, then, she has n-1 possibles options and n-2 that are not correct and after that, she has n-2 possibles options and 1 give her a successful login.

Finally, no matter what is the value of k, the probability that her first successful login will be (exactly) on her k-th try is 1/n

You might be interested in
I mark brianlest just help me;-;
Rina8888 [55]

Answer:

B)113.04 cm^2

Step-by-step explanation:

8 0
2 years ago
Read 2 more answers
BRAINLIEST if correct<br><br><br><br><br> 4
Viefleur [7K]

Answer:

Yes it is biased

Step-by-step explanation:

It shows favoritism

4 0
3 years ago
Read 2 more answers
How do you solve d+12=2 using mental math
n200080 [17]
By minusing 12 to both sides
d+12=2
   -12=-12
d      =-10
5 0
3 years ago
In a G.P the difference between the 1st and 5th term is 150, and the difference between the
liubo4ka [24]

Answer:

Either \displaystyle \frac{-1522}{\sqrt{41}} (approximately -238) or \displaystyle \frac{1522}{\sqrt{41}} (approximately 238.)

Step-by-step explanation:

Let a denote the first term of this geometric series, and let r denote the common ratio of this geometric series.

The first five terms of this series would be:

  • a,
  • a\cdot r,
  • a \cdot r^2,
  • a \cdot r^3,
  • a \cdot r^4.

First equation:

a\, r^4 - a = 150.

Second equation:

a\, r^3 - a\, r = 48.

Rewrite and simplify the first equation.

\begin{aligned}& a\, r^4 - a \\ &= a\, \left(r^4 - 1\right)\\ &= a\, \left(r^2 - 1\right) \, \left(r^2 + 1\right) \end{aligned}.

Therefore, the first equation becomes:

a\, \left(r^2 - 1\right) \, \left(r^2 + 1\right) = 150..

Similarly, rewrite and simplify the second equation:

\begin{aligned}&a\, r^3 - a\, r\\ &= a\, \left( r^3 - r\right) \\ &= a\, r\, \left(r^2 - 1\right) \end{aligned}.

Therefore, the second equation becomes:

a\, r\, \left(r^2 - 1\right) = 48.

Take the quotient between these two equations:

\begin{aligned}\frac{a\, \left(r^2 - 1\right) \, \left(r^2 + 1\right)}{a\cdot r\, \left(r^2 - 1\right)} = \frac{150}{48}\end{aligned}.

Simplify and solve for r:

\displaystyle \frac{r^2+ 1}{r} = \frac{25}{8}.

8\, r^2 - 25\, r + 8 = 0.

Either \displaystyle r = \frac{25 - 3\, \sqrt{41}}{16} or \displaystyle r = \frac{25 + 3\, \sqrt{41}}{16}.

Assume that \displaystyle r = \frac{25 - 3\, \sqrt{41}}{16}. Substitute back to either of the two original equations to show that \displaystyle a = -\frac{497\, \sqrt{41}}{41} - 75.

Calculate the sum of the first five terms:

\begin{aligned} &a + a\cdot r + a\cdot r^2 + a\cdot r^3 + a \cdot r^4\\ &= -\frac{1522\sqrt{41}}{41} \approx -238\end{aligned}.

Similarly, assume that \displaystyle r = \frac{25 + 3\, \sqrt{41}}{16}. Substitute back to either of the two original equations to show that \displaystyle a = \frac{497\, \sqrt{41}}{41} - 75.

Calculate the sum of the first five terms:

\begin{aligned} &a + a\cdot r + a\cdot r^2 + a\cdot r^3 + a \cdot r^4\\ &= \frac{1522\sqrt{41}}{41} \approx 238\end{aligned}.

4 0
3 years ago
In rectangle JKLM, JK is equal to 10 feet and MN is equal to 25 feet, find JL.
Snezhnost [94]

we know that

if JKLM is a rectangle

then

diagonals

MK=JL

so

MK=2*MN------> MK=2*25 ft------> MK=50 ft

JL=MK----> JL=50 ft


therefore


the answer is

JL is 50 ft

7 0
3 years ago
Other questions:
  • Which expression is equivalent to 36 ÷ 4? 4 ÷ 36 36 ÷ x 36 x
    5·1 answer
  • (3x^2y)(7x^2y)(-2x^2y)
    12·2 answers
  • I need help with a MathsWatch question!
    14·2 answers
  • Based on the polynomial remainder theorem, what is the value of the function when x = 4? f(x)=x4−2x3+5x2−20x−4
    15·2 answers
  • What does y=mx+ b represent
    5·2 answers
  • A doctor takes an uber from the airport to a hotel. The uber driver charges an $2.50 initial charge plus $2.65 per mile? Which e
    8·1 answer
  • Determine the height in meters of a triangle with an area of 72 square meters and a base of 28 meters.​
    10·1 answer
  • Somebody please help I hate geometry
    9·1 answer
  • Help me on this please:(
    5·1 answer
  • Yasmine worked on HW when she got home.
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!